Function to modify a variable not working - Javascript

Question

My issue concern 3 variables :

var modifyForce = 2;
var forceBase = 15;
var Force = (forceBase + modifyForce);

It display 17 Force

The first function which is working is :

{
    Force++;
    document.getElementById("Force").innerHTML = Force;
}

It adds +1 to Force each time I call it

But the second function :

{
    forceBase++;
    document.getElementById("Force").innerHTML = Force;
}

Does not add +1 to Force. Since it should add +1 to forceBase and Force = forceBase + modifyForce then it should add 1 to Force... I think.

My goal is to have a "forceBase" statistic + a "modifyForce" in order to get a total of "Force"

I am probably missing something simple but I can't find what. :/

Thank you :)

You need to manually update Force, there is no references.

epascarello
– epascarello

2015-02-11 13:52:53 +00:00
Commented Feb 11, 2015 at 13:52 — epascarello
– epascarello, Commented Feb 11, 2015 at 13:52

David Reeve · Accepted Answer · 2015-02-11 13:52:50Z

2

The problem is you're not updating Force to be equal to the new forceBase + modifyForce. Beyond declaration, Force doesn't keep any connection to forceBase or modifyForce, and you have to manually assign the new value to it. You should change your code as such:

{
    forceBase++;
    Force = forceBase + modifyForce;
    document.getElementById("Force").innerHTML = Force;
}

Keep in mind that if Force is changed in another function (such as the first one you posted), this will reset those changes.

answered Feb 11, 2015 at 13:52

David Reeve

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3 Comments

epascarello Over a year ago

@NaeemShaikh What in the world are you talking about?.

Naeem Shaikh Over a year ago

op thinks force is already incremented say upto 20, then again reinitializing to Force = forceBase + modifyForce; will get it back to 12

epascarello Over a year ago

@NaeemShaikh That is not the issue.... The issue is the fact the OP thinks that when you add two numbers, they will automatically update the calculation when either of the two numbers is increased/decreased.

Chris Charles · Accepted Answer · 2015-02-11 13:58:02Z

2

No one seems to have suggested this yet...

If you want Force to always be forceBase + modifyForce then make it a function.

function Force(){
    return forceBase + modifyForce
}

Which now makes this work (note Force is now called with ():

{
    forceBase++;
    document.getElementById("Force").innerHTML = Force();
}

answered Feb 11, 2015 at 13:58

Chris Charles

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1 Comment

Amit Joki Over a year ago

and there is no need for it to. @R3tep

fortiZ · Accepted Answer · 2015-02-11 14:00:04Z

2

var modifyForce = 2;
var forceBase = 15;
var Force = (forceBase + modifyForce);

Force is one time calculated with forceBase + modifyForce After the declaration you just have the number saved in Force

If you would like to use Force as a function to add modifyForce to forceBase use something like

var Force = function () {
    return forceBase + modifyForce;
}

but you can't increment it like Force++ :P

answered Feb 11, 2015 at 14:00

fortiZ

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Comments

Philipp · Accepted Answer · 2015-02-11 13:57:04Z

1

The code-block where you edit forceBase does not re-calculate the updated value of Force.

To make this simple I recommend you move the re-calcultation and output into a distinct function like this:

var modifyForce = 2;
var forceBase = 15;

function updateForce() {
    var Force = (forceBase + modifyForce);
    document.getElementById("Force").innerHTML = Force;
}

// Output the current value of Force
updateForce(); // output is 17

forceBase++;
updateForce(); // output is 18

modifyForce++;
updateForce(); // output is 19

answered Feb 11, 2015 at 13:57

Philipp

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Comments

David P · Accepted Answer · 2015-02-11 14:05:05Z

1

The best thing might be to create a class:

var objForce = {
    modifyForce: 2,
    forceBase: 15,
    Force: 17,
    reCalculate: function() { 
        this.Force = this.modifyForce + this.forceBase;
    }
};
objForce.forceBase++;
objForce.reCalculate();
document.getElementById("Force").innerHTML = objForce.Force;

answered Feb 11, 2015 at 14:05

David P

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